
//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/classes/binary-parser [v1.0]


BinaryParser = function( bigEndian, allowExceptions ){
	this.bigEndian = bigEndian;
	this.allowExceptions = allowExceptions;
};
with( { p: BinaryParser.prototype } ){
	with( {p: ( p.Buffer = function( bigEndian, buffer ){ this.bigEndian = bigEndian || 0; this.buffer = []; this.setBuffer( buffer ); } ).prototype } ){
		p.setBuffer = function( data ){
			if( data ){
				for( var l, i = l = data.length, b = this.buffer = new Array( l ); i; b[l - i] = data.charCodeAt( --i ) );
				this.bigEndian && b.reverse();
			}
		};
		p.hasNeededBits = function( neededBits ){
			return this.buffer.length >= -( -neededBits >> 3 );
		};
		p.checkBuffer = function( neededBits ){
			if( !this.hasNeededBits( neededBits ) )
				throw new Error( "checkBuffer::missing bytes" );
		};
		p.readBits = function( start, length ){
			//shl fix: Henri Torgemane ~1996 (compressed by Jonas Raoni)
			function shl( a, b ){
				for( ; b--; a = ( ( a %= 0x7fffffff + 1 ) & 0x40000000 ) == 0x40000000 ? a * 2 : ( a - 0x40000000 ) * 2 + 0x7fffffff + 1 );
				return a;
			}
			if( start < 0 || length <= 0 )
				return 0;
			this.checkBuffer( start + length );
			for( var offsetLeft, offsetRight = start % 8, curByte = this.buffer.length - ( start >> 3 ) - 1, lastByte = this.buffer.length + ( -( start + length ) >> 3 ), diff = curByte - lastByte, sum = ( ( this.buffer[ curByte ] >> offsetRight ) & ( ( 1 << ( diff ? 8 - offsetRight : length ) ) - 1 ) ) + ( diff && ( offsetLeft = ( start + length ) % 8 ) ? ( this.buffer[ lastByte++ ] & ( ( 1 << offsetLeft ) - 1 ) ) << ( diff-- << 3 ) - offsetRight : 0 ); diff; sum += shl( this.buffer[ lastByte++ ], ( diff-- << 3 ) - offsetRight ) );
			return sum;
		};
	}
	p.warn = function( msg ){
		if( this.allowExceptions )
			throw new Error( msg );
		return 1;
	};
	p.decodeFloat = function( data, precisionBits, exponentBits ){
		var b = new this.Buffer( this.bigEndian, data );
		try{
			b.checkBuffer( precisionBits + exponentBits + 1 );
		}catch(e){
			throw new Error( "decodeFloat::missing bytes" );
		}
		var bias = Math.pow( 2, exponentBits - 1 ) - 1, signal = b.readBits( precisionBits + exponentBits, 1 ), exponent = b.readBits( precisionBits, exponentBits ), significand = 0,
		divisor = 2, curByte = b.buffer.length + ( -precisionBits >> 3 ) - 1;
		do
			for( var byteValue = b.buffer[ ++curByte ], startBit = precisionBits % 8 || 8, mask = 1 << startBit; mask >>= 1; ( byteValue & mask ) && ( significand += 1 / divisor ), divisor *= 2 );
		while( precisionBits -= startBit );
		return exponent == ( bias << 1 ) + 1 ? significand ? NaN : signal ? -Infinity : +Infinity : ( 1 + signal * -2 ) * ( exponent || significand ? !exponent ? Math.pow( 2, -bias + 1 ) * significand : Math.pow( 2, exponent - bias ) * ( 1 + significand ) : 0 );
	};
	p.decodeInt = function( data, bits, signed ){
		try{
			var b = new this.Buffer( this.bigEndian, data ), x = b.readBits( 0, bits ), max = Math.pow( 2, bits );
		}catch(e){
			throw new Error( "decodeInt::missing bytes" );
		}
		return signed && x >= max / 2 ? x - max : x;
	};
	p.encodeFloat = function( data, precisionBits, exponentBits ){
		var bias = Math.pow( 2, exponentBits - 1 ) - 1, minExp = -bias + 1, maxExp = bias, minUnnormExp = minExp - precisionBits,
		status = isNaN( n = parseFloat( data ) ) || n == -Infinity || n == +Infinity ? n : 0,
		exp = 0, len = 2 * bias + 1 + precisionBits + 3, bin = new Array( len ),
		signal = ( n = status !== 0 ? 0 : n ) < 0, n = Math.abs( n ), intPart = Math.floor( n ), floatPart = n - intPart,
		i, lastBit, rounded, j, result;
		for( i = len; i; bin[--i] = 0 );
		for( i = bias + 2; intPart && i; bin[--i] = intPart % 2, intPart = Math.floor( intPart / 2 ) );
		for( i = bias + 1; floatPart > 0 && i; ( bin[++i] = ( ( floatPart *= 2 ) >= 1 ) - 0 ) && --floatPart );
		for( i = -1; ++i < len && !bin[i]; );
		if( bin[( lastBit = precisionBits - 1 + ( i = ( exp = bias + 1 - i ) >= minExp && exp <= maxExp ? i + 1 : bias + 1 - ( exp = minExp - 1 ) ) ) + 1] ){
			if( !( rounded = bin[lastBit] ) )
				for( j = lastBit + 2; !rounded && j < len; rounded = bin[j++] );
			for( j = lastBit + 1; rounded && --j >= 0; ( bin[j] = !bin[j] - 0 ) && ( rounded = 0 ) );
		}
		for( i = i - 2 < 0 ? -1 : i - 3; ++i < len && !bin[i]; );
		if( ( exp = bias + 1 - i ) >= minExp && exp <= maxExp )
			++i;
		else if( exp < minExp ){
			exp != bias + 1 - len && exp < minUnnormExp && this.warn( "encodeFloat::float underflow" );
			i = bias + 1 - ( exp = minExp - 1 );
		}
		if( intPart || status !== 0 ){
			this.warn( intPart ? "encodeFloat::float overflow" : "encodeFloat::" + status );
			exp = maxExp + 1;
			i = bias + 2;
			if( status == -Infinity )
				signal = 1;
			else if( isNaN( status ) )
				bin[i] = 1;
		}
		for( n = Math.abs( exp + bias ), j = exponentBits + 1, result = ""; --j; result = ( n % 2 ) + result, n = n >>= 1 );
		for( n = 0, j = 0, i = ( result = ( signal ? "1" : "0" ) + result + bin.slice( i, i + precisionBits ).join( "" ) ).length, r = []; i; j = ( j + 1 ) % 8 ){
			n += ( 1 << j ) * result.charAt( --i );
			if( j == 7 ){
				r[r.length] = String.fromCharCode( n );
				n = 0;
			}
		}
		r[r.length] = n ? String.fromCharCode( n ) : "";
		return ( this.bigEndian ? r.reverse() : r ).join( "" );
	};
	p.encodeInt = function( data, bits, signed ){
		var max = Math.pow( 2, bits );
		( data >= max || data < -( max >> 1 ) ) && this.warn( "encodeInt::overflow" ) && ( data = 0 );
		data < 0 && ( data += max );
		for( var r = []; data; r[r.length] = String.fromCharCode( data % 256 ), data = Math.floor( data / 256 ) );
		for( bits = -( -bits >> 3 ) - r.length; bits--; r[r.length] = "\0" );
		return ( this.bigEndian ? r.reverse() : r ).join( "" );
	};
	p.toSmall    = function( data ){ return this.decodeInt( data,  8, true  ); };
	p.fromSmall  = function( data ){ return this.encodeInt( data,  8, true  ); };
	p.toByte     = function( data ){ return this.decodeInt( data,  8, false ); };
	p.fromByte   = function( data ){ return this.encodeInt( data,  8, false ); };
	p.toShort    = function( data ){ return this.decodeInt( data, 16, true  ); };
	p.fromShort  = function( data ){ return this.encodeInt( data, 16, true  ); };
	p.toWord     = function( data ){ return this.decodeInt( data, 16, false ); };
	p.fromWord   = function( data ){ return this.encodeInt( data, 16, false ); };
	p.toInt      = function( data ){ return this.decodeInt( data, 32, true  ); };
	p.fromInt    = function( data ){ return this.encodeInt( data, 32, true  ); };
	p.toDWord    = function( data ){ return this.decodeInt( data, 32, false ); };
	p.fromDWord  = function( data ){ return this.encodeInt( data, 32, false ); };
	p.toFloat    = function( data ){ return this.decodeFloat( data, 23, 8   ); };
	p.fromFloat  = function( data ){ return this.encodeFloat( data, 23, 8   ); };
	p.toDouble   = function( data ){ return this.decodeFloat( data, 52, 11  ); };
	p.fromDouble = function( data ){ return this.encodeFloat( data, 52, 11  ); };
}
